THE Shooters and Fishers Party have helped doom a NSW Greens bill to ban coal-seam gas in the Northern Rivers by voting against the legislation despite earlier this morning promising privately to support it.

The Petroleum (Onshore) Amendment (Prohibit Coal Seam Gas) Bill would have enabled the government to cancel CSG licences without compensation and put a stop to any future gas mining on the Northern Rivers.

Much was made of the likely chances of the bill getting through the Upper House this week after intensive negotiations between the Greens, Labor and the minor parties led to what was predicted to be a majority when the bill went to a vote.

But after being introduced by Greens MLC Jeremy Buckingham the bill was voted down 16-19 after a short debate.

Earlier in the day Christian Democrat leader Fred Nile declared in a joint press conference with Labor and the Greens declaring he would be "on the right side of history" in supporting the bill.

Likewise, it's understood the Shooters and Fishers had suggested they would support the legislation.

Lock the Gate national coordinator Phil Laird said his group had been talking to the Shooters and Fishers "extensively" about the bill for the last two to three months.

"We were surprised when the Shooters and Fishers voted with the government," he said.

Mr Laird said the Shooters and Fishers had conducted their own enquiry into the East Coast gas supply which concluded a moratorium on the industry was acceptable until certain recommendations by the NSW Chief Scientist on the industry were introduced.

"We were very hopeful they would support the bill," Mr Laird said.

Local Nationals MLC Ben Franklin, who has been outspoken in his views against CSG on the Northern Rivers in the past, also voted with his party against the bill.